Field-induced slow magnetic relaxation and luminescence thermometry in a mononuclear ytterbium complex

Abstract

The mononuclear complex [Yb(H₃L^1,1,4)]·2MeOH (1·2MeOH), with a new heptadentate N₄O₃ ligand, was isolated and structurally characterised. The opto-magnetic properties of 1·2MeOH were investigated, showing that this complex is a bifunctional compound. Accordingly, 1·2MeOH reveals two coexisting functionalities: field-induced single molecule magnet behaviour, and Yb³⁺-centred NIR fluorescence dependent on temperature (25–300 K). The magnetic relaxation in this pentagonal bipyramidal complex does not seem to be of the Orbach type, and this is supported by the discrepancy between the anisotropic energy barrier found by fitting the magnetic data to an Orbach model and by spectroscopic studies. Ab initio calculations further validate the magnetic relaxation mechanisms and spectroscopic results.